C ++按值擦除向量元素

Question

I have a vector with Cards and i need to find card and remove it . I tryed the code below but I am getting error: binary '==': no operator found which takes a left-hand operand of type 'Card'

The code makes sense to me. Could you give me some tips how to make it works? Thanks!

void Player::RemoveCardFromPackage(const Card& cardToBeRemoved)
{    
    std::vector<Card>::iterator position = std::find(CadrVector.begin(), CadrVector.end(), cardToBeRemoved);
    if (position != CadrVector.end())
    {
        CadrVector.erase(position);
    }
}

Answer 1

How do you expect std::find() to know how to compare two elements of your custom type CadrVector ? When two of these elements are considered equal and when not? You have to define that.

So either pass a comparator to the fourth argument of std::find() , or overload the == operator of your type.

Answer 2

You can try find_if instead, with custom compare function:

#include <iostream>
#include <algorithm>
#include <vector>

class Card
{
    int c;
public:
    Card(int c): c(c) {}
    int GetC() const { return c; }
};

std::vector<Card> CardVector;

class Player 
{
public:
    void RemoveCardFromPackage(const Card& cardToBeRemoved);
};

void Player::RemoveCardFromPackage(const Card& cardToBeRemoved)
{

    auto found = std::find_if(CardVector.begin(), CardVector.end(), [&cardToBeRemoved](Card const &card) 
    {
        return cardToBeRemoved.GetC() == card.GetC();
    });

    if (found != CardVector.end())
    {
        CardVector.erase(found);
    }
}

int main()
{
    Player p;
    Card c1(1);
    CardVector.push_back(c1);
    Card c2(2);
    CardVector.push_back(c2);
    Card c3(3);
    CardVector.push_back(c3);

    std::cout << "Before:\n";
    for (size_t i = 0; i < CardVector.size(); ++i)
        std::cout << "Card C: " << CardVector[i].GetC() << " ";

    p.RemoveCardFromPackage(c2);

    std::cout << "\n\nAfter:\n";
    for (size_t i = 0; i < CardVector.size(); ++i)
        std::cout << "Card C: " << CardVector[i].GetC() << " ";

    return 0;
}

Prints:

Before:
Card C: 1 Card C: 2 Card C: 3

After:
Card C: 1 Card C: 3